IPAC2011 - List of Authors (Montesinos, E.)

Paper	Title	Page
MOPC056	The Linac4 Power Coupler	208
	F. Gerigk, J.-M. Giguet, E. Montesinos, B. Riffaud, P. Ugena Tirado, R. Wegner CERN, Geneva, Switzerland
	Linac4 employs 3 types of accelerating structures after the RFQ: a Drift Tube Linac (DTL), a Cell-Coupled DTL (CCDTL), and a Pi-Mode Structure (PIMS) to accelerate the beam to 160 MeV. The structures are designed for a peak power of 1 MW per coupler, which consists of two parts: a ceramic window, which separates the cavity vacuum from the air in the wave-guides, and a so-called "coupling T", which couples the RF power through an iris to the cavity. In the frame of the Linac4 R&D both devices have been significantly improved with respect to their commonly used design. On the coupler side, the wave-guide short circuit with its matched length has been replaced by a fixed length λ/4 short circuit. The RF matching is done by a simple piston tuner, which allows a quick matching to different cavity quality factors. In the window part, which usually consists of a ceramic disc and 2 pieces of wave-guides with matching elements, the wave-guide sections could be completely suppressed, so that the window became very compact, lightweight, and much simpler to manufacture. In this paper we present electromagnetic simulations, and tests on first prototypes, which were constructed at CERN.

MOPC058	Upgrade of the 200 MHz RF System in the CERN SPS	214
	E.N. Shaposhnikova, E. Ciapala, E. Montesinos CERN, Geneva, Switzerland
	The 200 MHz RF system, used in the SPS to accelerate all beams including those for the LHC, has four travelling wave structure cavities of different length. To stabilize the future higher intensity LHC beams in the SPS a larger (than now) controlled longitudinal emittance blow-up and therefore larger bucket and voltage amplitude will be necessary. However less voltage will be available in the existing system (which has a maximum peak RF power of 1 MW per cavity) due to the increased beam loading, in particular in the long cavities. This issue will be critical for beam acceleration but especially for beam transfer into the 400 MHz RF system of the LHC. The proposed solution is to shorten the two long cavities and use the freed sections together with spare sections to make two extra cavities and install two new power plants of 1.3 MW each. After this upgrade, which is a major part of the more general SPS upgrade for high luminosity LHC to be completed during 2017, the performance of the SPS RF system with high intensity beams will be significantly improved and at the same time the total impedance of the system will be reduced.

TUPS103	High Temperature Radio Frequency Loads	1783
	S. Federmann, F. Caspers, A. Grudiev, E. Montesinos, I. Syratchev CERN, Geneva, Switzerland
	In the context of energy saving and recovery requirements the design of reliable and robust RF power loads which permit a high outlet temperature and high pressure of the cooling water is desirable. Cooling water arriving at the outlet with 150 deg C and more than 20 bar has a certain value. Normal RF power loads containing dielectric and sensitive windows usually do not permit going much higher than 50 deg C. Here we present and discuss several design concepts for narrow-band “metal only” RF high power loads. One concept is the application of normal steel corrugated waveguides structures near cutoff .This concept could find practical use above several GHz. Another solution are resonant structures made of normal magnetic steel to be installed in large waveguides for frequencies of 500 MHz or lower. Similar resonant structures above 100 MHz taking advantage the rather high losses of normal steel may also be used in coaxial line geometries with large dimensions.

Paper

Title

Page

The Linac4 Power Coupler

208

F. Gerigk, J.-M. Giguet, E. Montesinos, B. Riffaud, P. Ugena Tirado, R. Wegner
CERN, Geneva, Switzerland

Linac4 employs 3 types of accelerating structures after the RFQ: a Drift Tube Linac (DTL), a Cell-Coupled DTL (CCDTL), and a Pi-Mode Structure (PIMS) to accelerate the beam to 160 MeV. The structures are designed for a peak power of 1 MW per coupler, which consists of two parts: a ceramic window, which separates the cavity vacuum from the air in the wave-guides, and a so-called "coupling T", which couples the RF power through an iris to the cavity. In the frame of the Linac4 R&D both devices have been significantly improved with respect to their commonly used design. On the coupler side, the wave-guide short circuit with its matched length has been replaced by a fixed length λ/4 short circuit. The RF matching is done by a simple piston tuner, which allows a quick matching to different cavity quality factors. In the window part, which usually consists of a ceramic disc and 2 pieces of wave-guides with matching elements, the wave-guide sections could be completely suppressed, so that the window became very compact, lightweight, and much simpler to manufacture. In this paper we present electromagnetic simulations, and tests on first prototypes, which were constructed at CERN.

MOPC058

Upgrade of the 200 MHz RF System in the CERN SPS

214

E.N. Shaposhnikova, E. Ciapala, E. Montesinos
CERN, Geneva, Switzerland

The 200 MHz RF system, used in the SPS to accelerate all beams including those for the LHC, has four travelling wave structure cavities of different length. To stabilize the future higher intensity LHC beams in the SPS a larger (than now) controlled longitudinal emittance blow-up and therefore larger bucket and voltage amplitude will be necessary. However less voltage will be available in the existing system (which has a maximum peak RF power of 1 MW per cavity) due to the increased beam loading, in particular in the long cavities. This issue will be critical for beam acceleration but especially for beam transfer into the 400 MHz RF system of the LHC. The proposed solution is to shorten the two long cavities and use the freed sections together with spare sections to make two extra cavities and install two new power plants of 1.3 MW each. After this upgrade, which is a major part of the more general SPS upgrade for high luminosity LHC to be completed during 2017, the performance of the SPS RF system with high intensity beams will be significantly improved and at the same time the total impedance of the system will be reduced.

TUPS103

High Temperature Radio Frequency Loads

1783

S. Federmann, F. Caspers, A. Grudiev, E. Montesinos, I. Syratchev
CERN, Geneva, Switzerland

In the context of energy saving and recovery requirements the design of reliable and robust RF power loads which permit a high outlet temperature and high pressure of the cooling water is desirable. Cooling water arriving at the outlet with 150 deg C and more than 20 bar has a certain value. Normal RF power loads containing dielectric and sensitive windows usually do not permit going much higher than 50 deg C. Here we present and discuss several design concepts for narrow-band “metal only” RF high power loads. One concept is the application of normal steel corrugated waveguides structures near cutoff .This concept could find practical use above several GHz. Another solution are resonant structures made of normal magnetic steel to be installed in large waveguides for frequencies of 500 MHz or lower. Similar resonant structures above 100 MHz taking advantage the rather high losses of normal steel may also be used in coaxial line geometries with large dimensions.